USB2SER Data Sheet, Rev. 0

Functional Description

Freescale Semiconductor

8

Each USB peripheral requires a unique VID/PID combination. Vendor IDs are assigned by the USB-IF. It is possible to us the

factory VID/PID combination, only if the Product strings are not modified. In case that the strings are changed, it is necessary

to get a different VID/PID combination.

Freescale, as a member of the USB-IF, owns a Vendor ID and manages a database of Product IDs to be used in association with

the VID. If a customer of Freescale’s USB-enabled products is unable to procure their own VID, apply to use Freescale’s VID

in association with an assigned PID.

In case the device loses power in the middle of a descriptors configuration process, the default parameters will be loaded to

ensure that the part remains functional in all cases. If this happens, the password to protect the device from further modifications

will also be reset to the default value which is “FFFFFFFFFFFFFFFF”

2

Functional Description

The USB2SER is a USB2.0 Full Speed (12Mb/s) to the UART (RS232 or RS485) converter. This device integrates an on-chip

Full Speed USB 2.0 compatible transceiver, the USB serial interface engine, and an on-chip 3.3 V voltage regulator to a UART

communication.

2.1

Crystal frequency auto-detection

The USB2SER supports 2MHz, 4MHz, 6MHz, 8MHz, 12MH, and 16MHz external crystals connected in a Pierce Oscillator

Configuration.

Figure 6. Pierce Oscillator

2.2

Operating errors

USB_LED

. The following are the possible errors and the device expected behavior:

•

For a PLL issue (crystal outside the operating range) the gray sequence changes every 60 ms

•

For a USB issue the sequence changes every 200 ms

2.3

RS232 connections

Figure shows the recommended connections to an RS232 transceiver. When interfacing to an RS485 transceiver, the

RS485_TXEN controls the transmitter enable signal.